Across much of the Midwest in 2020, observed soybean yields were well above expectations.1 This is not to say that average to below-average soybean yields were not experienced, but overall yields were excellent across much of the soybean growing area in the U.S. So, what was it about 2020 that allowed soybeans to excel and can this be replicated in 2021?
In my opinion, it was a combination of positive factors, including early planting, well-timed precipitation, normal to slightly above-normal temperatures, plenty of sunlight, low disease incidence and improved genetics.
Early planting: Like corn, soybean plants benefit from early planting and planting into good soil conditions. Early planting allows for earlier canopy development and more nodes prior to flowering (Figure 1). This ultimately produces a larger “factory” for photosynthesis and a longer growing season for growth, development and pod fill.
Uniform emergence: Most of the soybean crop across the region was planted into good seedbed conditions, which allowed for uniform emergence and most plants to have an equal footing with neighboring plants.
Increased node development: Early planting and normal to above-normal temperatures through July and August in combination with ample moisture helped promote node and leaf development. The canopy was able to capture available sunlight and convert it into photosynthate and allowed for abundant flowering sites at each node (Figures 2 and 3).
Abundant sunlight: The combination of early planting and increased nodes sets the stage to capture abundant sunlight in July and August. Experience has shown me that summers with more sunny days than cloudy days typically lead to increased soybean yields. Soybeans, like most other crops, benefit from increased photosynthesis and put that benefit into seed weight (yield).
Fertility: More emphasis has been placed on fertilizing soybeans over the past few years, which, in my opinion, has produced additional bushels, particularly in high-yielding years. We don’t think of soybeans as a secondary crop anymore and fertilize it like a cash crop.
Low to moderate drought stress: One of the more interesting factors was the presence of below-normal precipitation across much of the region. Typically, this would mean reduced soybean yields, but in my opinion, the combination of early planting, improved genetics and reduced disease presence (due to dry conditions) allowed soybean plants to push through the three-to-six-week dry spell without much reduction in potential yield.
Low disease pressure: In many areas, below-normal precipitation in the mid-to-late season helped to reduce disease incidence. Where diseases occurred, early planting may have helped offset negative impacts from the disease.
Improved genetics: With the absence of many common biotic and abiotic stressors, this was the year that allowed the improved genetics in soybeans to really shine and exploit their true yield potential.
So, can the yields of 2020 be repeated? Absolutely, but only if the same “high yield” management strategies outlined are repeated, which can help set the potential for high yields. Then Mother Nature will need to cooperate once more to provide the ideal soybean growing conditions.
1Schnitkey, G., Paulson, N., Swanson, K., and Zulauf, C. Corn and soybean yield in 2020. Farmdoc daily (10):174, Department of Agricultural and Consumer Economics, University of Illinois at Urbana-Champaign, September 29, 2020. https://farmdocdaily.illinois.edu/2020/09/corn-and-soybean-yield-in-2020.html.
Websites verified 11/20/2020.
Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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